Load tap selector for tapped transformers with several contact circles per phase



Get. 5, 1954- B JANSEN LOAD TAP SELECTOR FOR TAPPED TRANSFORMERS WITH SEVERAL CONTACT CIRCLES PER PHASE Filed. March 7, 1951 INVENTOR:

ATTO R N EYS Patented Oct. 5, 1954 UNITED OFFICE LOAD TA]? SELECTOR FUR TAPPED TRANS- FORMERS WITH SEVERAL CONTACT CIR- CLES PER PHASE Application March 7,

6 Claims.

This invention relates to load switches for tapped transformers having several rows of contacts per phase.

Load selectors for tapped transformers are connected without the insertion of a step selector with the transformer taps and take care of the selectin and load switching on the same contact row. In the already known load switches, the stationary switch contacts connected with the transformer taps are uniformly distributed on the periphery of a circular or cylindrical contact carrier, generally an insulating late or insulated cage consisting of bars or an insulated cylinder. Within this stationary contact circle, the system of movable load switch contacts with their contact resistances, serving for the switching of the load, move from contact to contact tangentially or on chords or on cycloidal paths or similar paths. This movable contact system is evenly directed towards the radial central axis of the main (in case of multi-phase load selectors towards the radial central axis of all main contacts to be switched at the same time) and regulates the correct time sequence of the connections and disconnections of the movable load switch contacts by arrangement of the corresponding contact guides on axes which lead or lag behind the radial central axis by a certain angle. In this connection, however, the angular displacement of the axes always remains in the range of one switching step as determined by the angular distance between two adjacent stationary tap contacts on the external contact carrier.

Improvements made recently in the field of load switches cannot be applied to the known load switches whose arrangement of switch contacts cannot limited to the angular distance between two stationary tap contacts. They must be distributed over the entire periphery of the inner circular or cylindrical contact carrier and accordingiy cannot be connected with the same tap contacts in the case of a changeover switchin opera-- tion, which is, however, necessary in order to maintain the correct switching sequence.

In accordance with the present invention, this difficulty is overcome by providing an entire circle or group of spaced stationary switch contacts arranged circumferentially on the outer circular or cylindrical contact carrier and connected with the individual transformer taps for each movable load switch contact on the inner circular or cylindrical contact carrier. For instance, there are thus produced, along with the customary movable main contact directly connected with the current shunt and with the two movable auxiliary contacts connected with the main contact by means of switch resistances, three such groups of contacts. These groups of contacts can, for instance, operate in three horizontal planes displaced axially with respect to each other in the longitudinal direction of the load selector. During this switching operation, the stationary switch contacts belongin to difierent circles or groups, but belonging to the same transformer tap, are electrically connected with each other on the outer contact carrier, while the movable switch contacts on the inner contact carrier are connected positively and mechanically with each other by a common contact lever. If the axially displaced contact circles or groups of contacts are arranged far enough apart from each other on the outer contact carrier, the conductors required for connection between the stationary,

main and auxiliary contacts of the same transformer tap can be arranged in multi-screw thread formation in the intermediate spaces produced thereby. The insulation of these conductors against the voltage potential of the adjacent conductors and contacts is suitably efiected by winding layers of cable paper thereon.

It is the main object of the present invention to provide a load selector for tapped transformers that is highly eflicient in operation and compact and simple in construction.

Other objects and advantages of the invention will be apparent from the description thereof to follow taken in connection with the accompanyin drawings in which-- In the drawings,

Fig. 1 is a part elevational and part sectional view of a load switch having an outer and an inner cylindrical or tubular contact carrier, embodying my invention.

Fig. 2 is a cross-sectional view taken on the plane of the line ha-ha of Fig. 1.

Fig. 3 is a cross-sectional view taken on the plane of the line H-I-I of Fig. 1.

Fig. l is a cross-sectional view taken on the plane of the line hbhb of Fig. 1.

In 1, a load switch is shown including an outer tubular or cylindrical load switch contact carrier and an inner tubular or cylindrical. load switch contact carrier. The upper halves of the contact carriers are in longitudinal section to show the arrangement of the spaced stationary and movable load switch contacts. The contacts are arranged in groups and the individual contacts of each group are circumferentially spaced from each other. The groups are axially spaced from each other, with the upper group disposed on the plane of the line ha-ha, the intermediate groupon the plane of the line HH, and the lower group on the plane of the line hb-hb of -Fig. l.

The lower halves of the contact carriers are in elevation showing the helical course of the insulated. connecting lines between the three stationary contacts belonging to each transformer tap.

In Fig. 3 are shown the main stationary load contacts Hi to Hit} disposed in the central or intermediate plane indicated by the line HH of Fig. 1. These contacts are suitably fastened to the inner surface of the outer contact carrier and spaced circumferentially therearound.

Fig. 2 shows the lagging auxiliary stationary contacts ha! to halt] on the upper plane indicated by the line harha of Fig. 1, and Fig. 4 shows the leading auxiliary stationary load contacts hbl to hblii on the lower plane indicated by the line h'o-hb of Fig. 1. These auxiliary contacts are mounted on the inner surface of the outer carrier and spaced circumferentially therearound.

A rotatable tubular shaft m is suitably supported centrally of the inner contact carrier and extends through the area occupied by the three groups of stationary contacts. A triangular or spider-shaped plate Si is fastened to the top end of the tubular shaft and a similar shaped plate S2 is fastened to the bottom end of the shaft. Insulating levers or push rods Li and L2 are pivotally connected to two of the pointed ends of plate Si and similar levers or push rods L3 and L4 are pivotally connected to the bottom plate S2. The outer free ends of the levers or push rods are operatively connected to movable load switch contacts Kl, K2 and K3. Interposed in any suitable operative manner between the upper movable auxiliary switch load contact and the lower auxiliary movable switch contact K3 and connected to the movable switch contacts are ohmic resistance elements Us and U1).

In the intermediate or centrol plane indicated by the line I-I-H of Fig. 1, the main switch load stationary contacts Hi to Eli) are supported on the inner surface of the outer contact carrier and arranged circumferentially in spaced relation therearound. The main movable switch contact Kl is arranged in this plane and is adapted to contact the stationary contacts in said plane.

In the upper plane indicated by the line of Fig. 1, the stationary auxiliary switch contacts hal to halt] are supported on the inner surface of the outer contact carrier and arranged circumferentially in spaced relation therearound. The auxiliary movable switch contact Ka is also arranged in this plane and is adapted to contact the stationary contacts in said plane.

In the lower plane indicated by the line hb-hb of Fig. 1, the auxiliary stationary switch contacts hbl to hblfl are supported on the inner surface of the outer contact carrier and arranged circumferentially in spaced relation therearound. The auxiliary movable switch contact K3 is also arranged in this lower plane and is adapted to contact the stationary contacts in said plane.

The stationary load contacts provided with the same index number, for example, H5, ME and M25, are positioned in staggered relation about 120 apart and are electrically connected to each other by the connections or conductors shown in helical formation at the bottom of Fig. 1, and connected to the transformer tap bearing the same index number.

The movable load switch contacts including the main contact KI and the auxiliary contacts K2 and K3 are electrically connected with the current shunt A directly or by means of the ohmic switch resistances U0. and U19 (Fig. 3). They are mechanically connected to the central tubular shaft m by means of the levers Ll, L2, L3 and L4, the spider plates SI and S2. The main movable contact Kl is connected to the levers LI and L3 by means of a rod T extending between and connected to said levers. The auxiliary movable contacts K2 and K3 are connected to shaft m by the links or levers L2 and L4.

A torque is imparted to the rotatable shaft m by coil springs FI and F2 acting upon the spider plates SI and S2, respectively, which torque forces the movable contacts Kl, K2 and K3 radially outward until one of them comes into contact with one of the stationary load stationary contacts, bringing the latter into circuit with the transformer winding and the current shunt A. Thus as shown in the drawing, at the top of Fig. 1 and in Fig. 3, the main movable contact Kl is moved into contact with the stationary top contact H5 and electrically connects the latter directly with the current shunt A.

The auxiliary movable contacts K2 and K3 are actuated only upon the switching of the load from one transformer stage to another, for example, from contact H5 to contact H t. During this switching operation, the inner cylindrical contact carrier rolls in the known manner in the outer cylindrical contact carrier, for instance, from contact H5 to H6, H1, H8, Ht, His), Hi, H2, H3 to H4 as viewed in Fig. 3. During this switching movement, the movable main contact Kl moves in a cycloidal path from contact H3 to H4. Before contact Kl moves from contact H5, movable contact K3 (Fig. -l) is moved into contact with contact 71125 and in this wa maintains the continuous electric connection from con tact H5 via contact 71b5, movable contact K3 and the switch resistance Ub to the current shunt A.

Continued further rolling of the inner cylindrical contact carrier brings movable contact K2 (Fig. 2) into contact with contact Before contact K3 is moved away from contact 72b5, an electrical connection is established from contact H1: through contact ha l, movable contact K2 and the contact resistance Ua to the current shunt A. Continued further rolling beyond contact ha4 carries movable contact Kl into contact with the tap contact H4 and brings the latter into direct electric connection with the current shunt A. In this way, the load switching from contact H3 to contact H4 is completed.

A current interruption has not taken place during this switching movement inasmuch as springs FI and F2 always impart a torque on the mechanical devices of the system consisting of the three-armed spider plates SI and S2, the central tube m, the levers Ll, L2, L3, L4, and the supporting rod T, which torque the movable contacts KI, K2 and K3 displace outwardly as far as possible in a radial direction so that each passing contact can only move from its stationary mating contact when the contact moving up already has touched its coacting stationary contact. This is only possible when the auxiliary movable contacts K2 and K3 have a sufficiently large angle, for example, about as compared with the main movable contact KI. The corresponding stationary engaging contacts must therefore be rotated over the main contacts (for example, H5 and H4, respectively) as to cover this same angle with smooth electrical action.

I claim:

1. In a load selector for tapped transformers having a large number of taps of the type consisting of stationary and movable load switch contacts and ohmic contact resistances connected to same, said stationary load switch contacts being connected with the individual transformer taps and arranged in an insulated manner, a switching device including a contact carrier carrying said stationary contacts and having an externally cylindrical shape, said movable load switch contacts cooperating with the stationary load switch contacts and a current shunt connected therewith; a contact carrier carrying said ohmic contact resistances and being of substantially cylindrical shape, means allowing said last carrier to roll eccentrically in the outer contact carrier, including means whereby each movable load switch contact cooperates with a circle of stationary load switch contacts corresponding to it, and conductors rigidly and mechanically connecting the stationary load switch contacts belonging to different circles but to the same transformer tap.

2. A switching device according to claim 1 in. which said movable load switch contacts are arranged approximately uniformly over the entire periphery of the inner movable contact carrier, in which the circles of the stationary load switch contacts, with each of which a separate movable load switch contact cooperates, are arranged axially displaced from each other on the cylindrical surface of the outer carrier, and in which the metallic connections between the stationary load switch contacts belonging to the same transformer tap are arranged in the intermediate spaces between the axially displaced contact circles in a multi-screw-thread formation.

3. A switching device for a tapped transformer having a plurality of taps including an outer tubular member having rows of axially spaced stationary contacts on its inner surface, the individual contacts of each row being spaced circumferentially, means of connection between said stationary contacts and the transformer taps, an

inner tubular member rollable on the contacts on said outer tubular member, a rotatable shaft supported centrally of said inner tubular member and radially movable contacts carried by said shaft for contacting the stationary contacts, and means including coiled springs for moving said shaft, the stationary contacts of different rows connected to one transformer tap being connected to each other, and also including in cooperative relationship with the means for moving said shaft, plates fastened at the respective ends of said shaft, insulating levers pivotally connected, respectively, at the inner ends, to predetermined points of both said plates, the outer ends of said insulating levers being operatively connected to the respective movable contacts.

4. A switching device for a tapped transformer having a plurality of taps including an outer tubular member having rows of axially spaced stationary contacts on its inner surface, the individual contacts of each row being spaced circumferentially, means of connection between said stationary contacts and the transformer taps, an inner tubular member rollable on the contacts on said outer tubular member, a rotatable shaft supported centrally of said inner tubular memher, a movable contact carried by said shaft opposite each row of stationary contacts adapted to contact said stationary contacts, and means for moving said shaft, and also including in cooperative relationship with the means for moving said shaft, plates fastened at the respective ends of said shaft, insulating levers pivotally connected, respectively, at the inner ends, to predetermined points of both said plates, the outer ends of said insulating levers being operatively connected to the respective movable contacts.

5. A. switching device for a tapped transformer having a plurality of taps including an outer tubular member having rows of axially spaced stationary contacts on its inner surface, the individual contacts of each row being spaced circumferentially, an inner tubular member rollable on the contacts on said outer tubular member, a rotatable shaft supported centrally of said inner tubular member, a movable contact carried by said shaft opposite each row of stationary contacts adapted to contact said stationary contacts, and coiled springs for moving said shaft, and means of connection between the stationary contacts and the transformer taps, the stationary contacts of different rows connected to one transformer tap being connected to each other, said connections being disposed in the spaces between the rows of stationary contacts, and also including in cooperative relationship with the means for moving said shaft, plates fastened at the respective ends of said shaft, insulating levers pivotally connected, respectively, at the inner ends, to predetermined points of both said plates, the outer ends of said insulating levers being operatively connected to the respective movable contacts.

6. A switching device for a tapped transformer having a plurality of taps including an outer tubular member having rows of axially spaced stationary contacts on its inner surface, the individual contacts of each row being spaced circumferentially, an inner tubular member rollable on the contacts on said outer tubular member, a rotatable shaft supported centrally of said inner tubular member, a movable contact carried by said shaft opposite each row of stationary contacts adapted to contact said stationary contacts, coiled springs for moving said shaft, and conductors connecting stationary contacts of different rows to one transformer tap and to each other, said conductors being disposed in the spaces between the rows of contacts and being arranged in helical formation, and also including in cooperative relationship with the means for moving said shaft, plates fastened at the respective ends of said shaft, insulating levers pivotally connected, respectively, at the inner ends, to predetermined points of both said plates, the outer ends of said insulating levers being operatively connected to the respective movable contacts.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,931,869 Jansen Oct. 24, 1933 2,231,627 Jansen Feb. 11, 1941 FOREIGN PATENTS Number Country Date 705,659 Germany May 6, 1941 

